1. Field of the Invention
The invention relates to multipin connectors including filtering means. More specifically, the invention relates to such connectors wherein the filtering means comprise a ferrite material.
2. Description of Prior Art
Electronic devices which use high frequency pulse trains, such as computers, can generate signals which will cause radio frequency interference (RFI) and electromagnetic interference (EMI) to nearby radio and other electronic devices. The signals leak out through interconnecting, multipin connectors referred to as D connectors. Interference signals can also leak into the electronic devices through the same connectors.
Attempts have been made to include filtering means on the connectors to filter the EMI and RFI signals to ground, or to attenuate them so that they are no longer of significant amplitude. The connectors include openings through which the pins of the D connectors extend, and one of the filtering means consists of capacitors connected between openings to provide a high impedance path for the high frequency signals. Another approach is to have a small bead of ferrite material surround a portion of each pin. The ferrite bead is then covered with a thin layer of conductive material (silver) to again provide a high impedance capacitive path to the high frequency interference signals.
The problem with the capacitive approach is capacitors are subject to dielectric breakdown due to high signal strength of the interfering signals, environmental conditions, or aging of the dielectric. In addition, the connectors using capacitive filters are difficult and expensive to produce.
Other approaches for providing filtering for multipin connectors are shown in U.S. Pat. No. 3,487,353, Dec. 30, 1969, Massa, U.S. Pat. No. 3,727,169, Apr. 10, 1973, Crane et al, U.S. Pat. No. 3,868,162, Feb. 25, 1975, Ammon and U.S. Pat. No. 4,364,626, Dec. 21, 1982, Price.
The '353 patent teaches a multi-contact connector which includes a solid block of insulating material 37 (see FIG. 2). The patent does not identify the type of insulator material which is to be used.
The '169 patent teaches a multipin connector wherein the pins are embedded in the dielectric material (see FIG. 10) as mentioned at Column 4, lines 5 and 6, the '169 patent contemplates rigid plastic as the dielectric material.
The '162 patent teaches a D-type connector in association with a substrate 14 which comprises an insulative substrate with plated through holes. The '626 patent teaches a connector arrangement 10 including an insulative housing 12. The insulative housing has a plurality of through holes, and a separate wire passes through each of the through holes. Once again, the material of the insulator is not mentioned in the patent.
The '626 patent illustrates a further multipin connector.